I think I've damaged the nipple thread in my Primus no.5 burner when fitting several nipples recently (none of them sustained a flame - think the jet dia is too small). The original nipple won't fit back in, I believe Base Camp sell a repair nipple with a tapered thread. Are these any good - is the threaded section longer than the normal parallel one? Does anyone have a pic of this part please? Paul.
@Paraffinhead I don’t have one Paul but as an original Primus solution to the problem I expect it’d work, maybe helped with a thin smear of graphite grease. Acetylene lanterns have burners (essentially a jet) that have conical threads, but they’re not operating at the pressure of a pressure stove. You say that your burner won’t sustain a flame because the jet is too small. Not likely. Jet orifice on a No.5 is 0.32mm diameter. Some Primus 71 stoves take a jet with a 0.23mm hole, which would still vapourise a No.5, but with a lesser maximum output. Possibility that the jets you’ve been using required a lot of pricking - if there’s dirt in the fuel tank or burner riser that can happen and it’s fighting a losing battle until you’ve cleaned out the tank and riser and used fresh filtered fuel. Then again, the burner tubing might be partially blocked with fuel deposits. Like de-coking a car engine it would need to be de-coked. Usual technique is to remove it from the stove, heat it to dull red with a blowtorch and tap out the dislodged deposits, using an airline (jet removed) if you’ve access to one. That said, a silent burner for a No.5, even if not a Primus original is a common enough find on ebay or other sources. That at least would continue to take ‘regular’ jets and you’d not need to bother with a tapered ‘repair’ jet. Welcome to CCS! John
@Paraffinhead I have tried resorting to the 'repair' jets that you refer to a couple of times. The difference between the repair jets and standard jets is that, while they are the same length, the repair jet threads are tapered. The taper out to a wider top shoulder is to compensate for worn burner (female) threads. Unfortunately I have to say that I have not found their use very helpful. They are not self-tapping and the older Primus catalogues indicate that they were designed to be used with special taper taps which are no longer available. If you can get a new jet back in, but find it can't be got to seal round the seating area, a smear of exhaust sealant on the threads can sometimes provide a solution of sorts. Hope this is helpful. Ian
Thanks for your replies. Firstly, the reason I suspect the replacement jets is that the original burned ok but with a lopsided flame - presumably an out-of-round orifice. None of the three replacements would sustain a burn after the preheat died, and it is impossible to get a pricker into the jet as the orifice is too small. Unfortunately it looks like I may have over-tightened the last of the replacements and having removed it I cannot get another nipple to "bite" the thread in the burner. I'm familiar with the heat-and-quench technique to clean out vapourisers on my pressure lamps but don't think this will solve my issue. I have a nice Sievert blowtorch which gets the tubes red-hot in no time. I have a couple of the stove repair kits from Kibworth DIY (hootflipflopandfly on ebay) which has a couple of NOS jets but can't get one to screw in, despite hours of trying. If all else fails I may try filing down the threads on a nipple & using exhaust paste to cement it in. I know I can get a replacement burner but that rather turns the stove into a bit of a "Trigger's broom". It only cost me £7 at a car boot and it's hardly a rare stove, I'd just rather have kept it as original as possible, as with all my paraffin-burning collection. I'll keep a lookout for an original Primus burner at reasonable cost. I'd be happy to hear from anyone with a spare Primus burner to sell. Paul.
Exhaust paste won't 'cement it in', if it helps at all it is only to assist in achieving a seal in the seating if there are tiny points of leakage there. It is always essential to have some level of viable threading. Some replacement jets can be hard to get started if they don't have much lead-in at the start of the threads, very careful work with a needle file can sometimes rectify that. So if you do any filing down just touch around the very bottom of the jet with the finest file you have.
Thanks for those words of wisdom - presumably the jet would become a projectile under pressure done my way! I think I'll experiment with one of the "non-runner" jets & make a taper so it drops in further down the thread. Paul.
